/* Test that malloc tcache catches double free.
Copyright (C) 2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <malloc.h>
#include <string.h>
/* Prevent GCC from optimizing away any malloc/free pairs. */
#pragma GCC optimize ("O0")
static int
do_test (void)
{
/* Do two allocation of any size that fit in tcache, and one that
doesn't. */
int ** volatile a = malloc (32);
int ** volatile b = malloc (32);
/* This is just under the mmap threshold. */
int ** volatile c = malloc (127 * 1024);
/* The invalid "tcache bucket" we might dereference will likely end
up somewhere within this memory block, so make all the accidental
"next" pointers cause segfaults. BZ #23907. */
memset (c, 0xff, 127 * 1024);
free (a); // puts in tcache
/* A is now free and contains the key we use to detect in-tcache.
Copy the key to the other chunks. */
memcpy (b, a, 32);
memcpy (c, a, 32);
/* This free tests the "are we in the tcache already" loop with a
VALID bin but "coincidental" matching key. */
free (b); // should NOT abort
/* This free tests the "is it a valid tcache bin" test. */
free (c); // should NOT abort
return 0;
}
#include <support/test-driver.c>